POS1180 CONCORDANCE IN THE CLASSIFICATION CRITERIA IN A PATIENT COHORT OF ANCA ASSOCIATED VASCULITIS
Authors: O. Iaremenko, L. Petelytska, V. Kravchenko
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Despite existing of different classifications criteria for ANCA-associated vasculitis (AAV), early diagnosing AAV is still challenging. Previous classification criteria do not include some of important diagnostic tests (for example, ANCA) or surrogate clinical markers and had insufficient specificity. According to the Vasculitis Patient-Powered Research Network study, the median time to diagnosis of vasculitis amounts 7 months and 73% of patients are misdiagnosed initially. Recently the American College of Rheumatology (ACR) and European Alliance of Associations for Rheumatology (EULAR) have proposed the new classification criteria for AAV, but they have not yet wildly used in a clinical practice. <h3>Objectives</h3> to evaluate the 2022 ACR/EULAR classification criteria for AAV in a Ukrainian patient cohort and compare it with the ACR 1990 classification criteria/ European Medical Agency (EMA) algorithm. <h3>Methods</h3> The retrospective study included 42 patients diagnosed between 2010 and 2022 with GPA, EGPA, MPA and undifferentiated vasculitis (UN) in two rheumatology centers from Ukraine. All patients have serology conformation (positivity of antibodies against proteinase-3 and/or myeloperoxidase performed using the ELISA test) and surrogate clinical markers of vasculitis. All cases were classified according to the 1990 ACR criteria, the 2007 EMA algorithm and reclassified according to the new ACR/EULAR 2022 criteria. If the patients do not meet the criteria of EGPA, MPA, or GPA, they are classified as UN. Concordance between different classification criteria and diagnosis was performed using Cohen's kappa coefficient with determination of sensitivity and specificity. <h3>Results</h3> Among 42 patients (female: male ratio 1:0.6) with AAV with mean age at the time of diagnosis of 47.19±11.55 years, 25 patients were diagnosed with GPA, 7 patients with EGPA, 7 patients with MPA and UV – 3 patients. According to the classification criteria of ACR 1990 and EMA 2007, 31 patients were diagnosed with GPA, EGPA – 4 patients, MPA – 1 patient, UV – 3 patients. Three patients simultaneously met the criteria for GPA and EGPA. When applying the new classification criteria, 24 patients were diagnosed with GPA, 5 patients with MPA, 5 patients with EGPA, and 4 patients with UV. Four patients simultaneously met the criteria for GPA and MPA. In total, in 28 patients the established diagnosis corresponded to the diagnosis according to the previous and new criteria, in 8 patients the diagnosis corresponded only to the new criteria (6 MPA, 1GPA, 1 UV), in 5 patients the diagnosis corresponded only to the classification criteria of ACR 1990 and the EMA algorithm (3 EGPA, 1 UV, 1 GPA), and one patient has not met any criteria. The new classification criteria compared to the previous ones demonstrated better agreement with the established diagnosis of GPA (k 0.6 vs 0.3, sensitivity 88.0% vs 92.0%, specificity 70.6% vs 35.3 %) and MPA (k 0.5 vs 0.2, sensitivity 71.4% vs 14.3%, specificity 88.6% vs 100%), but worse agreement with the diagnosis of EGPA (k 0.8 vs 1.0, sensitivity 71.4% vs 100%, specificity 100% vs 100%). The observed agreement between the two classification criteria was slight for GPA (k 0.3) and MPA (k 0.2), but substantial for EGPA (k 0.8). <h3>Conclusion</h3> The new ACR/EULAR 2022 classification criteria for ANCA-associated vasculitis demonstrate a high diagnostic value in the Ukrainian patient population (for GPA, sensitivity - 88%, specificity - 71%, for MPA - 71% and 89%, respectively, and for EGPA - 71% and 100%, respectively) and an advantage over the previous classification criteria for GPA and MPA. However, about 10% of the patients are unclassified and the same amount are matched two diagnoses with the new criteria. There is a slight agreement between ACR/EULAR2022 criteria and ACR1990 criteria/EMA algorithm for GPA and MPA. <h3>Reference</h3> [1]Sreih, A.G., Cronin, K., Shaw, D.G. <i>et al.</i> Diagnostic delays in vasculitis and factors associated with time to diagnosis. <i>Orphanet J Rare Dis</i><b>16</b>, 184 (2021). https://doi.org/10.1186/s13023-021-01794-5 <h3>Acknowledgements</h3> I have no acknowledgments to declare. <h3>Disclosure of Interests</h3> None Declared.